9945 has 24 divisors (see below), whose sum is σ = 19656. Its totient is φ = 4608.

The previous prime is 9941. The next prime is 9949. The reversal of 9945 is 5499.

It is a happy number.

9945 is nontrivially palindromic in base 2.

It is an interprime number because it is at equal distance from previous prime (9941) and next prime (9949).

It can be written as a sum of positive squares in 4 ways, for example, as 729 + 9216 = 27^2 + 96^2 .

It is not a de Polignac number, because 9945 - 2² = 9941 is a prime.

It is a Curzon number.

It is a nialpdrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9941) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 577 + ... + 593.

It is an arithmetic number, because the mean of its divisors is an integer number (819).

2⁹⁹⁴⁵ is an apocalyptic number.

It is an amenable number.

9945 is a deficient number, since it is larger than the sum of its proper divisors (9711).

9945 is a wasteful number, since it uses less digits than its factorization.

9945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41 (or 38 counting only the distinct ones).

The product of its digits is 1620, while the sum is 27.

The square root of 9945 is about 99.7246208316. The cubic root of 9945 is about 21.5047762960.

It can be divided in two parts, 994 and 5, that added together give a palindrome (999).

The spelling of 9945 in words is "nine thousand, nine hundred forty-five".